Cellular Energy

• What are the two laws of Thermodynamics?

  1. Energy can be converted from one form to another, but it cannot be created nor destroyed
  2. Energy cannot be converted without the loss of usable energy
• What is the difference between an anabolic pathway and a catabolic pathway?

  Anabolic pathways build larger molecules from smaller ones, requiring energy. Catabolic pathways break down larger molecules into smaller ones, releasing energy.
• How does ATP work in a cell?

  ATP (adenosine triphosphate) works in a cell by providing energy for cellular processes through its high-energy phosphate bonds. When ATP is hydrolyzed (broken down) into ADP (adenosine diphosphate) and inorganic phosphate, energy is released, which fuels various cellular activities such as muscle contraction, active transport, and synthesis of macromolecules.
• What are the two phase of photosynthesis?

  Light-dependent reactions and the Calvin Cycle (light independent reactions)
• What is the function of a chloroplast during the light reactions?

  The function of chloroplasts during light reactions is to absorb light energy and convert it into chemical energy in the form of ATP and NADPH through photosynthesis.
• How can electron transport be described and diagrammed?

  Electron transport is the movement of electrons through a series of protein complexes in the inner mitochondrial membrane during cellular respiration.
• What are the stages of cellular respiration?

  Glycolysis, Krebs cycle, Electron transport chain.
• What is the role of electron carriers in each stage of cellular respiration?

  Electron carriers transport electrons during cellular respiration, facilitating energy transfer. In glycolysis, NAD+ accepts electrons forming NADH. In the citric acid cycle, NAD+ and FAD accept electrons to form NADH and FADH2. In the electron transport chain, these carriers donate electrons, generating a proton gradient used to produce ATP.
• What are the similarities between alcoholic fermentation and lactic acid fermentation?

  Both alcoholic fermentation and lactic acid fermentation are types of anaerobic processes. They both begin with glycolysis, producing a net gain of two ATP molecules and converting glucose into pyruvate. However, instead of entering the aerobic respiration pathway, pyruvate is further metabolized into either ethanol and carbon dioxide in alcoholic fermentation or lactic acid in lactic acid fermentation.
• Trophic Level

  Each step in a food chain or food web
• Carbohydrate

  An organic compound containing carbon, hydrogen, and oxygen
• Cyanobacterium

  A type of eubacterium that is a photosynthetic autotroph
• Energy

  Ability to do work
• Thermodynamics

  Study of energy flow and transformation in the universe
• Metabolism

  All of the chemical reactions in a cell (Catabolic or Anabolic)
• Photosynthesis is the conversion of light energy from the sun to chemical energy to be used by the cell

  • Anabolic Reaction
  • 6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂
  • Carbon dioxide + water + sunlight energy →  Glucose + oxygen
  • Two Types of Reactions:
  • Light-dependent reaction
  • Calvin Cycle (Light-dependent reactions)
• Cellular Respiration is the breakdown of organic molecules to release energy to be used by the cell

  • Catabolic Reaction
  • How organisms obtain energy
  • 2 phases:
  • Aerobic Respiration
  • Glycolysis
• Adenosine Triphosphate (ATP)

  • Cellular energy is stored as ATP
  • Energy storage molecule used by most organisms
  • "Rechargable battery"
  • Energy conversions involve the release of energy stored as chemical bonds
• Thylakoid


  Flattened saclike membranes inside chloroplasts; location of the light-dependent reactions of photosynthesis
• Granum

  A stack of thylakoid membranes on the inside of chloroplasts
• Stroma


  The fluid-filled space outside the grana; location of the light-independent reactions of photosynthesis
• Pigment


  Molecules that absorb specific wavelengths of light
• NADP+


  Final electron-carrying molecule in light-dependent reactions; combines with electrons to form the energy storage molecule NADPH
• Phase 2: Calvin Cycle

  • Energy is stored in organic molecules such as glucose
  • Occurs in 3 phases: Carbon fixation, reduction, regeneration
• Rubisco


  An enzyme in the Calvin cycle that converts inorganic carbon molecules into organic molecules that can be used by the cell
• Anaerobic Respiration

  • Release of energy from food molecules without oxygen
  • The Anaerobic pathways that follow glycolysis
  • Anaerobic respiration is less efficient at extracting energy (only 2 ATP per glucose molecule)
  • 2 main types:
  • Lactic acid fermentation
  • Alcohol fermentation
• Aerobic Respiration

  • Breaks down pyruvate in the presence of oxygen
  • Converts pyruvate to CO2, H2O, and energy
  • Occurs in mitochondria
  • Involves the following stages:
  • Glycolysis
  • Formation of Acetyl-CoA
  • The Krebs Cycle
  • The electron transport chain and oxidative phosphorylation
• Glycolysis

  • Breakdown of glucose in the cytoplasm
  • 2 molecules of ATP and 2 molecules of NADH are formed for each molecule of glucose that is broken down
• Krebs Cycle

  • Series of reactions breaking down pyruvate into CO2
  • Glycolysis has a net result of 2 ATP and 2 Pyruvate
  • Most of the energy from the glucose is still contained in the pyruvate
  • The net yield from the Krebs Cycle is 6 CO2 molecules, 2 ATP, 8 NADH, and 2 FADH2
• Fermentation

  • When O2 is not available, cells use this process
  • Anaerobic Respiration
• Why are you sore during strenuous physical activity?

  During strenuous physical activity, your muscles demand more oxygen than your body can supply, leading to anaerobic metabolism. This produces lactic acid as a byproduct, which accumulates in muscles, causing soreness.
• Autotroph VS Heterotroph

  Autotroph: Organisms that make their own food

  Heterotroph: Organisms that need to ingest food to obtain energy
• Importance of ATP

  ATP (adenosine triphosphate) is the primary energy currency of cells. It provides energy for various cellular processes, including metabolism, muscle contraction, and active transport.
• Chemical equation for Photosynthesis and Cellular respirationPhotosynthesis:6CO2 + 6H2O + light energy → C6H12O6 + 6O2

  Cellular respiration:C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
• Aerobic Respiration vs. Anaerobic Respiration

  Aerobic respiration uses oxygen to break down glucose into energy, yielding more ATP (adenosine triphosphate) molecules compared to anaerobic respiration, which doesn't require oxygen and yields less ATP.
• Photosynthesis alternative Pathways (C4, CAM)

  • C4 plants
  • Fix carbon dioxide into four-carbon compounds instead of three-carbon compounds during the Calvin Cycle
  • Keep their stomata (pores) closed during hot days
  • Ex) Sugarcanes, Corn
  • CAM plants
  • Occurs in water-conserving plants that live in deserts and salt marshes where water is limited
  • Allow carbon dioxide to only enter at night and fix carbon dioxide into organic compounds
  • Ex) Cacti, orchids, pineapple
• Catabolic

  Build up larger molecules from smaller ones and use energy
• Anabolic

  Build up larger molecules into smaller molecules and release energy
• Summary of how the body uses ATP

  • ATP provides quick energy for cells when they need it
  • It's made of an adenosine molecule, a ribose sugar, and three phosphate groups.
• ATP Bond

  The bond between the second and third bond in the ATP molecule is unusually high in energy